1. Field of the Invention
Jet pumps have long been utilized in many industrial applications and are particularily useful for installation in the bottom of an oil well to effect the pumping of oil from the well. In general terms, a conventional jet pump provides a stream of fluid supplied from a pressure source at the surface of the well which is discharged at high velocity into a mixing chamber to which the fluid to be pumped is supplied, generally by an annular orifice surrounding the nozzle producing the jet stream. The mixing action of the jet stream on the fluid to be pumped converts the jet energy of the stream into sufficient pressure to pump the oil and supplied fluid to the top of the well.
When the fluid to be pumped contains any significant quantity of particulate material, and, in the case of oil wells, significant quantities of sand, there is a serious abrading or erosion effect on the walls of the mixing chamber produced by such particulate material which is necessarily impacted against such walls at relatively high speeds by the momentum transfer action of the high velocity jet. This necessitates frequent shut downs of the jet pump for replacement of the mixing chamber wall and hence is a significant factor impeding the production from an oil well or the operation of any other piece of industrial equipment in which the jet pump is employed.
2. Description of the Prior Art
The efforts employed in the prior art to increase the life of the mixing chambers of jet pumps have been primarily directed toward making the wall of the mixing chamber readily replaceable and developing abrasion resistant alloys for such replaceable wall portions. The prior art has not indicated that a more simple solution lies in providing a protective fluid screen within the mixing chamber to substantially prevent the particulate material from engaging the walls of the mixing chamber.